Revision of the stegocephalid genera Phippsia and Tetradeion (Crustacea: Amphipoda) with description of four new species

The stegocephalid (Crustacea: Amphipoda) genus Phippsia Stebbing, 1906 is revised to include six species, of which three are new to science. One new species of the genus Tetradeion Stebbing, 1899 is also described. A key to all species of the two genera is presented.